Wilbur l



W. L. MERRILL.

AUTOMATIC REVERSING CONTRUL.

APPLICATION man on. 14, 1921.

1 ,42 5,890. t ted Aug. 15, 1922.

Inventor: Wilbur L Merrill.

HisAnnornek unrreo STATES PATENT creme.

WILBUR L. MERRILL, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC-TRIC COMPANY, A CORPORATION OF, NEW Y0RK.-

' AUTOMATIC REVERSIHG oon'rnon.

To all whom it may concern:

'Be' it known that I, WILBUR L. MERRILL, a citizen of the UnitedStates','residing--at Schenectady, in the countyof Schenectady, StateotNew York, have invented certain new anduseful Improvements inAutomatic ReversingControls, of which the following isa specification.

My invention relates to an improved automatic reversing controlarrangement for controlling the electric driving motor of a machinewhich is intended tobe periodically reversed,"and the invention isdirected to the provision of a very simple and reliable control of thatnature. i 1

It is customary to providea pair of electro-magnetic reversing switchesfor controlling the" direction of operation of an electric driving motorand to control the energizetion of these switches by limit switchesoperated at the ,predetermined limits of travel of the machine. It isalsocustomary to interlock the reversing switches so that ,only one canbe closed at a' time, The usual arrangement is one in 'which'only thereversing switchwhich is clos ed is energized, so that to provide acontrolwh'ereby the reversing switches are alternately closed toperiodically reverse the motor at the limits of operation has involvedcomplications in the wiring.

In accordance with my invention, the reversing switches are arranged sothat only one can be closed at a time, but they are normally energizedso that all that is necessary to reverse the motor at a limit ofoperation is to temporarily deenergize the reversing switch which isclosed, thereby permitting the other reversing switch to close. Thereenergization of the first reversing switch produces no result untilthe motor operates to its other limit. The limit switches forcontrolling the reversin switches may therefore be normally close andonly one is temporarily opened at each limit of operation.

My invention also provides a simplified manual control whereby theoperator may select the initial direction of operation and whereby hemay at any time interrupt the automatic operation of the machine anddirect it manually as he desires.

\Vhile my invention is illustrated in connection with the drive of apastehoard or cardboard finishing machine since it has a Specificationof Letters Patent, Patented Aug; 15 1922 Application filed October 14,1921. 'Serial No. 507,732.

particular application thereto, the invention is notnecessarily'limitedto'suchan application. For a'bett'er understanding ofthe invention, reference is bad to the accompanying drawing wherein Ihave shown an embodiment of -my invention in the control of a reversiblecardboard finishing machine which' is driven bythe elec tri'c motorM.The armature circuit of this' ele'ctric motor adapted tolie-periodically reversed by the 'altei'nat -closing" of: theelectromagnetic reiversing svyfithes "or contactors"jl0-and *11. Thecontacto'r 10 is provided, ro'r connecting the*m otor to operate in theforward directi'onyfiand the contactor11"-is provided for connecting themotor to operate'in they're- 'versed direction, These reversing switchesare arr-angedso that only oneofthe switches can bef'close'd at one time,and to that end the 'pivoted mechanicalinterlock 12 is providedbetweemthe switches, so that when one of the switches is: closed, 'theotherwill beiiiechanically held open even though itswinding isenergized;

The windings of these reversing switches are connected so as to benormallyenergized during the operation of the motor between "itslimitsof travel, and the arrangement is such that, when the motor has:operated the machine s'o'tha't the article 13 operated upon by themachine comes into engagement with the limit switch 14, the forwardcontactor 10 is temporarily deenergized, and thereverse contactor 11 yis thereby permitted a) close. When the article 13, whic h maybe a pieceof cardboard operated'upon by, the machine, makes e ngagement jwith thelimit "switch 15, the ivinding (if the contactor 11 is deener'gized, andthe.contactor 10 is permitted to close to thereby reverse the motor 'andthe machine at the limit '.of operation. The limit switches 14 and 15'may be mountedso as to be adjnstable with respect to the rolls 16 and 17of the machine, so that the machine may be adjusted to take care ofdiflerent lengths of cardboard. The arrangement is such that after thelimit switches are once adjusted and the equipment started, the machinewill be periodi-,

may be termed a string 'relayf relay comprises a contact member 18movable contacts; the spring -22 1 is lengthened ,t h usl wt-th m nt -5the M nib r-li it etitr vel i si; ached.:5When Ja-meqeipmentisSWPPGduandIrBuemed; the r 9h. mh n $-.i s into err E se ent-Whats seeset ofroon actsgsbo ereb -..-,again -sh ovt i.. quit ifl eispontion 1,1; Betwe n the i tenfwgalsjof sp reti w rseedir c an anim et mm the Que-dire tors re s Ri ip rarily thejmptor ,circuimso as to. li it ra h:tcusrsn takenibytthe w f't fi lllfivfl al. '5? :-ZP1I-""IP'' AS 1 hsjcqn t 'z ctedt ds amass d-Abe eoperation' 'pf: my. invention; astollows ,In

. r. td'starb he; q iPment,; e-ma al y 3O sedated s as a s em qntrc dth. 3 qns a gdu qas slqsm s. wee ene t ierehy :ener ize .thewvmdmgs ofthe ,re-

ve sing'fswitc es L0. andll from the o'fsupply' 24. If it isdesiredgtoijstart the equipment in the forward direction,thenormallygclosedpush button 25 in the. coil cir; 'cuit,' ofthj'reiaerse; contactor 11-. will be depressed; by ltheyoperat'r;thereby :deenergizin'g t-he v; inding of 1thiscori actor and jprermttiiigthe forward contactor 10 to close. he push'bu'tton2'5 may bethenf'releesed jto energize the winding of therevjerse contactqr l1.Inasmuch as the forward contactor has closed the mechanical interlock1'2 willprei ent'the reverse contacton 11 from closing even though itswinding is energized. motor will be connected to the source of supply 24through the resistor R, but as soon as the equipment has operated for ashort interrah'the, switch member lS of the string relay will beoperated'so as to make engagement with its right hand set 'of stationarycontacts and thereby short circuit a portion of the resistor. Theinitial 'rush of current at starting is thereby protected against, andthe motor is permitted to accelerate to substantially full operatingspeed after. the machine-has started. If it is desired to start theequipment in'the reverse direction instead of in' the forwarddirectiomthe normally closed .push button 26 will be temporarilydepressed so as to permit the contactor 11 to first close.

'hen the left hand ,end of the cardboard 13 has been advanced so as tobe brought arranged to be ;.;free running. The:

into "engagement with the normally closed "Because' 'of-"the fact thatthe cnergization pfthe reyerse contactor 11 is n'iaintaincd, this'contactorwill immediately close and thereby reverse the direction ofcurrent sup plied to the motor armature. The contact member ,18 of: thestring relay will be permitted to break engagement with its right. handstationarycontacts and thereby rein troduce-i the protective resistanceR in the mot r -cirouitsfon an interval. An intervalafter-stilei'machinef'has begun operation in the-mtumdirection, thelimitswitch 14 is permitted to close so asto thereby reenergize- (the windingof the i'orwardcontaetor 10, and the switch member- 18 ofthe stringrelay is brought into- ;engagement with its lef hand $330.1; stationarycontacts to again shprt; circuit ,the portion of.. theproteeti ve irpsistp pR When the rightjhand-end of the is L brought intoengagement,withp the norrnally closed limit-switch 15., this limit switch isopened,-thereby deenergizinfitlre reverse contactor .11 and. permittinge forward contactor 10m close. The proteetiye' resistonR isavainincl-uded in the .Qqt0l;,. ;il: luit during the interval. of re-.is au tQmaticaLIycut outagain is. s ihwqaigmsnt-l .sev e ..;It;w.1llhas served from the'above that automatic reyeisal of theliiilqhlliewill'continue until the ,operatordcthat gtll equipment sh allstop. In orde r to stop; thecqulpment at any time, the man- Quellyope'rated control switch 23 will be lturnedto he position shown inthe drawing, thereby deenergizmg both the contractors 3.0

lL 'a ndj disconnecting the motor armatur'e from the source of supply.While the equipment is opcrati ng, if the operator do sires to efiectthe auwmatic revcrsal of 1111-: equi ment'befo're a limit of travel hasbeen "r'eac ed, he wnr temporarily depress the push vbutton 26 if themachine is being operated in the forward direction, or dcpn-ss'pushfbutton '25'if the 'rnachinc is opal-(Eng in the rererse direction.It the push bul- 'ton"26 is temporarily depressed while the -"machine'is. being operated in the 'lmrward directiom'fthc'equipment isautomatically rcvers'ed the same as if a limit of travel had beenreached. -The same is true of the effect 'of'o'perating the push button25 when the equipment is'opel'ating in the reverse direction. v I'twillbe apparent from the above that my arran eme'nt has obvious desirablefeatures of simplicity. The limit/switches 14 and 15 may be of thenormally closed type, and no complicated interlocking need be providedto insure that the automatic reversal of the equipment will be effectedas desired. In accordance with the provisions of the patent statutes, Ihave described the principle of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, but I desire to have it understood that the apparatus shown isonly illustrative and that the invention may be carried out by othermeans.

\Vhat I claim as new and desire to secure by Letters Patent of theUnited States, is

l. The combination with a reversible electric motor operable in eachdirection between predetermined limits, :1 pair of alternately closednormally energized electromagnetic reversing switches for controllingthe direction of operation of said mot/0r, means for preventing eitherof said switches from closing while the other is closed, and meanswhereby at each limit of operation of the motor the reversing switchwhich is closed is temporarily deenergized to permit the other reversingswitch to close and thereby reverse the motor and then energized whenthe motor is reversed so as to close when the said other reversingswitch is temporarily decnergized at the other limit of operation.

2. The combination with a reversible electric motor, of means forautomatically reversing the motor at predetermined limits of travel,comprising a pair of alternately closed normally energlzedelectromagnetic reversing switches for controlling the direction ofoperation of the motor, means for preventing either of said switchesfrom closing while the other switch is closed, a pair of normally closedlimit switches connected to be opened responsively to the operation ofthe motor, each of said limit switches controlling one of the saidreversin switches, and connections whereby the sai reversing switchesare alternately temporarily deenergized by the temporary opening of acorresponding limit switch at each limit of operation of the motor,

3. The combination with a machine, an article operated upon by themachine, an electric motor for driving the machine in a forward and areverse direction, a' pair of normally energized electromagneticreversing switches, adapted to be alternately closed, means forpreventing either of said switches from closing while the other switchis closed, limit switch mechanism operated by the said article forcontrolling the said reversing switches, and connections whereby thesaid reversing switches are alternately temporarily deenergized toperiodically reverse the motor as the limit switch mechanism is operatedby the said article at each limit of operation of the machine.

4. The combination withamachine and an electric motor connected theretofor driving the same in a forward and in a reverse direction, of anarticle operated upon by the machine, a pair of alternately closednormally energized electromagnetic reversing switches for controllingthe direction of operation of said motor, a mechanical connec tionbetween the said switches for preventing either switch from closingwhile the other is closed, a pair of normally closed limit switchesoperated by the said article, each of said limit switches controllingone of the said reversing switches, and connections whereb the saidreversing switches are alternate y temporarily deenergized toperiodically reverse the motor as a limit switch is operated by thearticle at each limit of operation of the machine.

5. The combination with a machine and an electric motor connectedthereto for driving the same in a forward and in a reverse directionbetween predetermined limits of operation, a pair of alternately closedelectromagnetic reversing switches for controlling the direction ofoperation of said motor, a mechanical connection between said reversingswitches for preventing either switch from closing while the other isclosed, manually operated switch mechanism for simultaneously energizingthe said reversin g switches, manually operated switch mechanism fortemporarily deenergizing one of the reversing switches to permit theother reversing switch to close, and means whereby at each limit ofoperation of the machine the reversing switch which is closed istemporarily deenergized to permit the other reversing switch to closeand thereby reverse the motor, and then energized when the motor isreversed so as to close when the said other reversing switch istemporarily deenerqized at the other limit of operation.

11 witness whereof, I have hereunto set my hand this 13th day ofOctober, 1921.

WILBUR L. MERRILL.

